Molecular identification of a glycoside hydrolase-producing bacterium of industrial interest

CAMINATA LANDRIEL SOLEDAD; RODRIGUEZ GASTÓN JORGELINA; FERRAROTTI SUSANA ALICIA; COSTA HERNAN

CIUDAD AUTONOMA DE BUENOS AIRES

Congreso; XLIX REUNION ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIO; 2013

SOCIEDAD ARGENTINA DE INVESTIGACION BIOQUIMICA Y BIOLOGIA MOLECULAR

Cyclodextrin Glucosyltransferase (CGTase), belonging to glycoside hydrolase family 13, catalyzes starch conversion into cyclodextrins and other industrial products. We have isolated a CGTase from a soil bacterium which had been classified as Bacillus circulans based on its phenotypic profile. Recently, the use of molecular tools has led to re-classification of microorganisms. The 16S rRNA gene is widely used for phylogenetic studies; however, its use is limited due to intragenomic heterogeneity. In addition, single-copy housekeeping genes are used, although there is no consensus about which of them should be employed. The aim of this work was to identify our CGTase-producing bacterium by molecular phylogenetic analysis of the 16S rRNA gene and the housekeeping genes gyrB, recA and tufA. These genes were amplified by PCR with degenerated primers and sequenced. Multiple sequence alignments including our sequences and curated nucleotide sequences from Bacillus and related genera were obtained with ClustalW software. The substitution model was inferred from each alignment with Modeltest. Phylogenetic trees were reconstructed by Maximum Likelihood and Maximum Parsimony criteria using PAUP. The reliability of each tree topology was performed by bootstrap (1000 pseudoreplicates). We conclude that the bacterium under study must be re-classified within the Paenibacillus genus.